Step 4 Search the literature

The search strategy for a systematic review needs to be as comprehensive as possible in order to capture all studies relevant to the review question. 

The general process in developing a search strategy is:

1. Identify synonyms and concepts related to the key concepts in your research question
2. Identify the databases and other sources you need to search 
3. Identify relevant database subject headings (e.g. MeSH - Medline, Emtree - Embase, etc) and apply to your search strategy
4. Apply search techniques such as Boolean, Nesting, Phrase Searching, Truncation and Wildcards
5. Consider if certain concepts/keywords require to be searched in particular database fields e.g. Title/Abstract
6. Consider if certain database filters need to be applied in order to narrow the search e.g. publication dates, age, sex, article type, language etc.
7. Test, review and amend search as required

A useful starting point can be to check the search strategies in published systematic reviews for examples of how searches are structured and assist in keyword development.

Your Liaison Librarian can provide you with assistance in developing search strategies.

Resources:

• Study Smart: Module 2: Identify and find information
• Checklist for Reviewing Search Strategies (Newcastle University)
• Building a search in Medline (Ebschohost)
• Building a search in Embase
• Building a search in PubMed

Systematic reviews require a meticulous documentation of their search strategy to enable a possible replication of their search in the future and a clear assessment of their quality. Most databases allow for the search history to saved which provides an exact record of the search.

Search details which must be recorded are;

• Sources searched, such as:
  • Databases (including the platform) e.g. EBSCO (platform) PsycINFO (database).
  • Hand searching a record of the source (for example, Conference proceedings, journal title) and years searched must be kept
  • Grey Literature sources
  • Organisations or experts contacted.
• The date the search was conducted and the period searched
• Subject headings and keywords used
• Search history, including the combination of terms and any restrictions applied such as Language.
• Number of results retrieved 
• Total number of records retrieved
• Duplicates identified

The numbers of search results are documented using the PRISMA Flow Diagram.

Resources:

• Systematic Review Worksheet.xlsx (University of Canberra)

It is important to establish a method for managing the search results retrieved via your search strategy.

• Reference management software such as EndNote is can be used for exporting all search results from final database searches so that duplicates can be removed and the records managed.
• Rayyan is a free tool with help guide for screening studies. See also the following guide.
• SUMARI is a tool with help guide for screening studies available through the QUT subscription to JBI Evidence-Based Practice
• Covidence (subscription) is an online systematic review program developed by, and for, systematic reviewers. It can import citations from reference managers like EndNote, facilitate the screening of abstracts and full-text, populate risk of bias tables, assist with data extraction, and export to all common formats. QUT has an institutional licence for Covidence. Be sure to use your QUT email address to request access.

Resources:

• Managing reviews in Endnote

Identify the relevant databases for your review. Your Liaison Librarian can advise on which databases should be searched and on developing search strategies.

Below are some of the key Health databases:

• Australian New Zealand Clinical Trials Registry Covers trials being undertaken in Australia, New Zealand on the therapeutic areas of pharmaceuticals, surgical procedures, preventive measures, lifestyle, devices, treatment and rehabilitation strategies and complementary therapies.
• ClinicalTrials.gov Database of federally and privately supported clinical trials conducted in the United States and around the world.
• Cochrane Central Register of Controlled Trials
• EU Clinical Trials Register
• Chinese Clinical Trial Registry A register for trials supported by Chinese Evidence-Based Medicine Center, Ministry of Health of the People’s Republic of China, West China Hospital, Sichuan University, and is a member of Ottawa Statement Group.
• Clinical Trials Registry India
• Internet Portal of the German Clinical Trials Register (DRKS)
• ISRCTN Register The ISRCTN is a numeric system for the unique identification of randomised controlled trials worldwide.
• Pan African Clinical Trials Registry
• WHO International Clinical Trials Registry Platform

Literature that is NOT published in traditional sources such as books and journals is referred to as “Grey Literature”.

Conference proceedings and theses are the most common types of Grey Literature in the academic context, but examples also include technical and research reports, government publications, policy papers, annual reports, fact sheets, maps, geological surveys and statistics.

See the following page for more information about Grey Literature.

Dissertations and Theses

• ProQuest Dissertations and Theses
• ProQuest Dissertations & Theses: UK & Ireland
• Trove : Australian Theses

Australian sources of grey literature

• Australian Institute of Health and Welfare
• State Health Departments
• National Health and Medical Research Council
• Australian Indigenous HealthInfoNet
• Department of Health and Ageing
• Australian University Research Repositories
• Australian Bureau of Statistics
• Australian Policy Online

 International sources of grey literature

• Policy Commons: Platform for think-tank publishing, grey literature, and government reports. 
• Overton: A searchable index of policy documents, guidelines, think tank publications and working papers from worldwide sources.
• World Health Organization
• The Grey Literature Report: The report is a bimonthly publication of The New York Academy of Medicine Library alerting readers to new grey literature publications in health services research and selected public health topics.
• Grey Matters: a practical search tool for evidence-based medicine: Published by The Canadian Agency for Drugs and Technologies in Health (CADTH). Provides details on where to locate grey literature in Australia and other countries.
• OpenGrey: System for Information on Grey Literature in Europe, is your open access to 700.000 bibliographical references of grey literature (paper) produced in Europe and allows you to export records and locate the documents.
• National Technical Information Service (U.S.): The National Technical Information Service is the largest central resource for U.S. government-funded scientific, technical, engineering, and business related information.
• OAIster: A union catalog of millions of records representing open access resources including theses, technical reports and research papers.
• Google: A search of Google using keywords and the advanced search functionality allows for limiting searches to specific domains such as government or research web sites. This can be useful for tracking down grey literature.
• PsychEXTRA: Covers technical, annual and government reports, conference papers, newsletters, magazines, newspapers and consumer brochures in  psychology.
• CogPrints: A self-archive for papers in any area of Psychology, Neuroscience, and Linguistics, and many areas of Computer Science.
• Mednar: A federated search engine of peer-reviewed medical resources. 
• OpenDOAR - Directory of Open Access Repositories

Hand searching is the manual examination of resources which are not indexed electronically, such as special issues of journals or conference proceedings.